linux-kernel - [PATCH] powerpc/8xx: Modify ptep

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Date:   Thu, 18 Jun 2020 12:07:46 +0000 (UTC)
From:   Christophe Leroy <christophe.leroy@...roup.eu>
To:     Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Michael Ellerman <mpe@...erman.id.au>,
        Will Deacon <will@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Peter Zijlstra (Intel)" <peterz@...radead.org>
Cc:     linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
        linux-mm@...ck.org
Subject: [PATCH] powerpc/8xx: Modify ptep_get()

Move ptep_get() close to pte_update(), in an ifdef section already
dedicated to powerpc 8xx. This section contains explanation about
the layout of page table entries.

Also modify it to return 4 times the pte value instead of padding
with zeroes.

Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 arch/powerpc/include/asm/nohash/32/pgtable.h | 22 +++++++++++---------
 1 file changed, 12 insertions(+), 10 deletions(-)

diff --git a/arch/powerpc/include/asm/nohash/32/pgtable.h b/arch/powerpc/include/asm/nohash/32/pgtable.h
index b0afbdd07740..b9e134d0f03a 100644
--- a/arch/powerpc/include/asm/nohash/32/pgtable.h
+++ b/arch/powerpc/include/asm/nohash/32/pgtable.h
@@ -249,6 +249,18 @@ static inline pte_basic_t pte_update(struct mm_struct *mm, unsigned long addr, p
 
 	return old;
 }
+
+#ifdef CONFIG_PPC_16K_PAGES
+#define __HAVE_ARCH_PTEP_GET
+static inline pte_t ptep_get(pte_t *ptep)
+{
+	pte_basic_t val = READ_ONCE(ptep->pte);
+	pte_t pte = {val, val, val, val};
+
+	return pte;
+}
+#endif /* CONFIG_PPC_16K_PAGES */
+
 #else
 static inline pte_basic_t pte_update(struct mm_struct *mm, unsigned long addr, pte_t *p,
 				     unsigned long clr, unsigned long set, int huge)
@@ -284,16 +296,6 @@ static inline pte_t ptep_get_and_clear(struct mm_struct *mm, unsigned long addr,
 	return __pte(pte_update(mm, addr, ptep, ~0, 0, 0));
 }
 
-#if defined(CONFIG_PPC_8xx) && defined(CONFIG_PPC_16K_PAGES)
-#define __HAVE_ARCH_PTEP_GET
-static inline pte_t ptep_get(pte_t *ptep)
-{
-	pte_t pte = {READ_ONCE(ptep->pte), 0, 0, 0};
-
-	return pte;
-}
-#endif
-
 #define __HAVE_ARCH_PTEP_SET_WRPROTECT
 static inline void ptep_set_wrprotect(struct mm_struct *mm, unsigned long addr,
 				      pte_t *ptep)
-- 
2.25.0